“Control of the substances” as used herein means activities aimed at reducing or maintaining constant or increasing these substances according to the well-known and broad meaning that is given to the word “control” in the “engineering” field; therefore “control of the substances” as used herein, means neither the simple verification of which substances are present nor simply the simple measurement of the amount of substances present:
The control of the substances present in a liquid, for example (but not only) water, has many practical applications.
There are several known methods for performing this operation; there are known methods of the physical type and known methods of the chemical type; there are known methods that operate on large families of substances and known methods that operate on just one or two substances.